The present invention relates to a power chuck, and more particularly to a master jaw which receives one of a plurality of insert jaws to retain a work piece without the necessity of repetitively attaching an entire jaw assembly to a power chuck.
Jaw assemblies are typically mounted to a rotatable chuck to retain a work piece so that machining operations can be performed thereon. Typically, each jaw assembly is tailored to a single particular work piece. To change over from one work piece to another the jaw assemblies must be replaced by another jaw assembly, which is tailored to the new work piece. Replacing a jaw assembly commonly requires removing a plurality of fasteners and replacing one jaw assembly with another. This is time consuming and requires care to accurately relocate the jaw assembly.
Accordingly, it is desirable to provide a jaw assembly that provides a quick and accurate changeover for a multiple of work pieces.
The jaw assembly according to the present invention includes a master jaw and an insert jaw. The jaw assembly is configured to retain a particular work piece such that only the insert jaw need be replaced when a changeover between one work piece to another is desired.
An engagement surface on the master jaw provides a mounting surface for an insert jaw. An insert fastener is mounted through an inset aperture centrally located through the engagement surface such that the insert jaw is reversibly mountable to engagement surface to thereby double the applications for each insert jaw. The master jaw is contoured to provide a minimum of mass opposite the mounting surface and opposite the engagement surface to minimize the total rotating mass when the jaw assembly is in operation.
In operation a force is applied substantially perpendicular to the engagement surfaces between the insert jaw and master jaw such that the engagement surface experiences the force rather than an insert jaw fastener. The insert fastener thereby need not be subjected to the substantial forces caused by machining operations. Excellent repeatability and concentricity is also maintained.
In another embodiment of the present invention a tension ring is positionable upon the master jaw such that removable alignment pegs fit within a corresponding alignment slot. Each alignment slot is preferably helically arranged on the ring such that the ring is adjustably located upon the pegs to provide an inward radial tension on the jaw assemblies which allows the insert jaws to be accurately machined to a desired shape to receive a specific work piece.
The present invention therefore provides a jaw assembly that provides a quick and accurate changeover for a multiple of work pieces.